/* 1. 设计令牌与 CSS 变量 */
:root {
  --color-bg: #F7F7F5;
  --color-surface: #FFFFFF;
  --color-surface-hover: #FCFCFB;
  --color-text-main: #202124;
  --color-text-regular: #3C4043;
  --color-text-muted: #6B7280;
  --color-text-light: #9CA3AF;
  
  --color-primary: #2B5B84;
  --color-primary-dark: #1E3F5F;
  --color-primary-light: #F0F5FA;
  
  --color-border: #E5E7EB;
  --color-border-light: #F0F0EE;
  
  --color-tag-bg: #EEF2F6;
  --color-tag-text: #374151;
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.03);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.04), 0 2px 4px -1px rgba(0, 0, 0, 0.02);
  --shadow-hover: 0 10px 15px -3px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.025);
  
  --max-width: 1120px;
  --article-width: 800px;
  
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif;
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 2. 基础与重置样式 */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-family: var(--font-family);
  font-size: 16px;
  line-height: 1.75;
  color: var(--color-text-regular);
  background-color: var(--color-bg);
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--color-bg);
  color: var(--color-text-regular);
}

img, svg {
  vertical-align: middle;
  max-width: 100%;
  height: auto;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-dark);
}

ul, ol {
  list-style-position: inside;
}

/* 3. 布局容器 */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

.article-container {
  width: 100%;
  max-width: var(--article-width);
  margin-left: auto;
  margin-right: auto;
}

.main-content {
  flex: 1 0 auto;
  padding-top: 2rem;
  padding-bottom: 4rem;
}

/* 4. 顶部导航栏 (Header) */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(247, 247, 245, 0.95);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
  transition: border-color var(--transition-fast);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.25rem;
}

.site-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text-main);
  letter-spacing: -0.01em;
}

.site-brand svg {
  width: 28px;
  height: 28px;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.nav-link {
  font-size: 0.975rem;
  font-weight: 500;
  color: var(--color-text-muted);
  padding: 0.4rem 0.6rem;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.nav-link:hover {
  color: var(--color-text-main);
  background-color: rgba(0, 0, 0, 0.03);
}

.nav-link.active {
  color: var(--color-primary);
  font-weight: 600;
  background-color: var(--color-primary-light);
}

/* 移动端菜单切换按钮 */
.menu-toggle {
  display: none;
  background: transparent;
  border: none;
  padding: 0.5rem;
  cursor: pointer;
  color: var(--color-text-main);
  border-radius: var(--radius-sm);
}

.menu-toggle:focus-visible {
  outline: 2px solid var(--color-primary);
}

.menu-toggle svg {
  width: 24px;
  height: 24px;
  display: block;
}

/* 5. Hero 区域 */
.hero-section {
  padding: 3.5rem 0 2.5rem;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: 3rem;
}

.hero-title {
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--color-text-main);
  line-height: 1.25;
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--color-primary);
  font-weight: 500;
  margin-bottom: 1rem;
}

.hero-description {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  max-width: 680px;
  line-height: 1.7;
}

/* 6. 栏目特色卡片 (Category Grid) */
.section-title-wrap {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 1.5rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--color-border);
}

.section-title {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-text-main);
}

.section-subtitle {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.cards-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-bottom: 3.5rem;
}

.feature-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-sm);
}

.feature-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
  border-color: #D1D5DB;
}

.card-header {
  margin-bottom: 1rem;
}

.card-icon {
  width: 42px;
  height: 42px;
  border-radius: var(--radius-sm);
  background-color: var(--color-primary-light);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
}

.card-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-text-main);
  margin-bottom: 0.5rem;
}

.card-desc {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

.card-footer {
  margin-top: 1.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--color-border-light);
}

.card-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-primary);
}

.card-btn:hover {
  color: var(--color-primary-dark);
}

/* 7. 文章列表与摘要 (Article List) */
.article-list {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.article-summary-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.5rem 1.75rem;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-sm);
}

.article-summary-card:hover {
  border-color: #D1D5DB;
  box-shadow: var(--shadow-md);
}

.article-meta {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 0.6rem;
}

.category-tag {
  display: inline-block;
  padding: 0.15rem 0.6rem;
  background-color: var(--color-tag-bg);
  color: var(--color-tag-text);
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 500;
}

.article-summary-title {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--color-text-main);
  margin-bottom: 0.6rem;
  line-height: 1.4;
}

.article-summary-title a {
  color: var(--color-text-main);
}

.article-summary-title a:hover {
  color: var(--color-primary);
}

.article-summary-text {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.65;
  margin-bottom: 0.75rem;
}

.read-more-link {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-primary);
}

/* 8. 栏目内专题文章完整呈现 (Full Article View) */
.page-intro-header {
  padding: 2.5rem 0 2rem;
  margin-bottom: 2.5rem;
  border-bottom: 1px solid var(--color-border);
}

.page-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-text-main);
  margin-bottom: 0.75rem;
}

.page-intro-text {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  max-width: 760px;
}

.article-full-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 2.25rem;
  margin-bottom: 2.5rem;
  box-shadow: var(--shadow-sm);
}

.article-full-card:last-child {
  margin-bottom: 0;
}

.article-full-header {
  padding-bottom: 1.25rem;
  margin-bottom: 1.5rem;
  border-bottom: 1px solid var(--color-border-light);
}

.article-full-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text-main);
  margin-bottom: 0.5rem;
  line-height: 1.35;
}

.article-body {
  font-size: 1rem;
  line-height: 1.8;
  color: var(--color-text-regular);
}

.article-body p {
  margin-bottom: 1.25rem;
}

.article-body h3 {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-text-main);
  margin-top: 1.75rem;
  margin-bottom: 0.75rem;
  padding-left: 0.6rem;
  border-left: 3px solid var(--color-primary);
}

.article-body ul, .article-body ol {
  margin-bottom: 1.25rem;
  padding-left: 1.25rem;
}

.article-body li {
  margin-bottom: 0.4rem;
}

.article-body blockquote {
  margin: 1.25rem 0;
  padding: 0.85rem 1.25rem;
  background-color: var(--color-bg);
  border-left: 4px solid var(--color-primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

.tip-box {
  background-color: var(--color-primary-light);
  border: 1px solid #D6E4F0;
  border-radius: var(--radius-sm);
  padding: 1rem 1.25rem;
  margin: 1.25rem 0;
  font-size: 0.95rem;
  color: #1A365D;
}

.tip-box strong {
  color: var(--color-primary-dark);
}

/* 9. 关于页面与 404 页面 */
.about-section {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 2.5rem;
  box-shadow: var(--shadow-sm);
}

.error-page-wrap {
  text-align: center;
  padding: 4rem 1.5rem;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.error-code {
  font-size: 4.5rem;
  font-weight: 800;
  color: var(--color-primary);
  line-height: 1;
  margin-bottom: 1rem;
}

.error-msg {
  font-size: 1.25rem;
  color: var(--color-text-main);
  font-weight: 600;
  margin-bottom: 0.75rem;
}

.error-desc {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  margin-bottom: 2rem;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.65rem 1.5rem;
  background-color: var(--color-primary);
  color: #FFFFFF;
  font-weight: 600;
  font-size: 0.95rem;
  border-radius: var(--radius-sm);
  transition: background-color var(--transition-fast);
}

.btn-primary:hover {
  background-color: var(--color-primary-dark);
  color: #FFFFFF;
}

/* 10. 页脚 (Footer) */
.site-footer {
  flex-shrink: 0;
  background-color: #FFFFFF;
  border-top: 1px solid var(--color-border);
  padding: 3rem 0 2rem;
  margin-top: auto;
}

.footer-top {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--color-border-light);
}

.footer-brand-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text-main);
  margin-bottom: 0.5rem;
}

.footer-brand-desc {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.6;
  max-width: 380px;
}

.footer-heading {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text-main);
  margin-bottom: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-links a {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.footer-links a:hover {
  color: var(--color-primary);
}

.footer-bottom {
  padding-top: 1.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-text-light);
}

.footer-icp {
  color: var(--color-text-muted);
  font-size: 0.85rem;
}

/* 11. 响应式断点控制 */
@media (max-width: 1023px) {
  .cards-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 767px) {
  .header-inner {
    height: 3.75rem;
  }
  
  .menu-toggle {
    display: block;
  }
  
  .site-nav {
    display: none;
    position: absolute;
    top: 3.75rem;
    left: 0;
    right: 0;
    background-color: #FFFFFF;
    flex-direction: column;
    padding: 1.25rem;
    gap: 0.75rem;
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-md);
  }
  
  .site-nav.is-open {
    display: flex;
  }
  
  .nav-link {
    width: 100%;
    padding: 0.6rem 0.8rem;
  }

  .hero-section {
    padding: 2.5rem 0 2rem;
    margin-bottom: 2rem;
  }
  
  .hero-title {
    font-size: 1.75rem;
  }
  
  .hero-subtitle {
    font-size: 1.05rem;
  }

  .cards-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
    margin-bottom: 2.5rem;
  }

  .article-full-card {
    padding: 1.5rem;
  }

  .about-section {
    padding: 1.5rem;
  }

  .footer-top {
    grid-template-columns: 1fr;
    gap: 1.75rem;
  }
}